This application contains subject matter which is related to the subject matter of the following applications, each of which is assigned to the same assignee as this application and each of which is hereby incorporated herein by reference in its entirety:
xe2x80x9cIsothermal Heat Sink With Converging, Diverging Channels,xe2x80x9d Chu et al., Ser. No. 09/502,321, co-filed herewith;
xe2x80x9cIsothermal Heat Sink With Cross-Flow Openings Between Channels,xe2x80x9d Chu et al., Ser. No. 09/501,640, co-filed herewith;
xe2x80x9cHybrid Cooling System For Electronics Module,xe2x80x9d Chrysler et al., Ser. No. 09/338,254, filed Jun. 22, 1999; and
xe2x80x9cEvaporator For use In An Extended Air Cooling System For Electronic Components,xe2x80x9d Chu et al., Ser. No. 09/052,416, filed Mar. 31, 1998.
The present invention is generally related to providing cooling systems for electronic devices requiring cooling. More particularly, the present invention is directed to an isothermal heat sink for uniformly cooling an electronics module.
In recent years, the semiconductor industry has taken advantage of the fact that CMOS circuits dissipate less power than bipolar circuits. This has permitted more dense packaging and correspondingly, faster CMOS circuits. However, almost no matter how fast one wishes to run a given electronic circuit chip, there is always the possibility of running it faster if the chip is cooled to lower temperatures during operation. This is particularly true of computer processor chips and even more true of these chips when they are disposed within multichip modules (MCMs), which generate significant amounts of heat. Because there is great demand to run processor modules at higher speeds, the corresponding clock frequencies at which these devices must operate become higher. In this regard, it should be noted that it is known that power generation rises in direct proportion to the clock frequency. Accordingly, the desire for faster computers generates not only demand for computer systems but generates thermal demand in terms of energy which must be removed for faster, safer and more reliable circuit operation. In this regard, it is to be particularly noted that, in the long run, thermal energy is the single biggest impediment to semiconductor operation integrity.
Multichannel heat sinks have been developed for extraction of heat generated by, for example, integrated electronic circuits, multi-chip modules, diode laser arrays, or other electro-optic devices under conditions of high heat flux density. Coolant flow in the channels is conventionally unidirectional, i.e., the coolant enters the heat sink through an inlet at one end and flows through parallel channels to an outlet at the other end.
An enhanced heat sink is described in U.S. Pat. No. 5,099,910, entitled xe2x80x9cMicrochannel Heat Sink With Alternating Flow Directions,xe2x80x9d the entirety of which is hereby incorporated herein by reference. Briefly summarized, this patent presents a heat sink wherein temperature rise along multiple parallel channels is addressed by providing alternating coolant flow directions through the channels of the heat sink. Although improving heat surface temperature distribution over the uniform flow direction approach, further enhancements are believed desirable to more closely achieve the goal of a truly isothermal heat sink for an electronic device.
Briefly described, the present invention comprises an apparatus for cooling an electronic device which includes a heat sink member with a surface for making thermal contact with the electronic device. The heat sink member includes a first plurality of channels and a second plurality of channels for carrying coolant fluid. The first plurality of channels comprises a first group of channels and a second group of channels, wherein the first group of channels and the second group of channels are positioned generally alternately across the member so that coolant fluid alternates direction therebetween. The second plurality of channels is disposed above the first plurality of channels such that the first plurality of channels and the second plurality of channels comprise tiered channels within the heat sink member. Further, the second plurality of channels comprises a third group of channels and a fourth group of channels, wherein the third group of channels and the fourth group of channels are positioned generally alternately across the member so that coolant flow alternates direction therebetween.
To restate, provided herein are various embodiments for attaining an isothermal heat sink for use in a cooling system of an electronic device. Enhanced performance of the cooling system is attained by more uniformly dissipating heat across the thermal interface surface of the heat sink, thereby more uniformly cooling the electronic device to which the heat sink is coupled. By more uniformly dissipating heat across the thermal interface surface, thermal resistance between the heat sink and electronic device is lowered. Further, since timing (synchronization) and noise tolerances are a function of electronic device temperature, maintaining circuits as isothermal as possible minimizes the temperature effect resulting in improved noise margin and clock skew. This effect is more pronounced in multichip modules.